Method of and apparatus for making spot crowns



Nov. 25,1941. F. .3. GAvlN Erm.

METHOD oF. AND APPARATUS Foa MAKING sPoT cRowNS Filed Sept.. 9, 1938Patented Nov. 25,1941

METHOD OF AND APPARATUS FonMAmNG sro'r cRowNs Frank J. Gavin, Scott IraWilbur, and Robert Hol-V land, Baltimore, Md., assignors to Crown Cork &Seal Company, Inc., Baltimore, Md., a corporation of New YorkApplication September 9, 1938, SeriaNo. 229,190'

13 Claims.

The present invention relates to a method of and apparatus for producingspot crowns. More particularly, the invention provides-'a new method andmeans for securing spot linersto the cushion discs of previouslyassembled crown closures.

It isI a primary object of the invention to simplify and to cheapen theoperation of securing spot liners to crown closures. The method'accomplishes all of the advantages of prior com- -mercial developmentsand can be used with standard assembly lines with only slight changesand Without reducing the speed of operation or i diminishing thecertainty of result.

According to standard practice in the art, the sheet material which isused to form spot liners .is coated on one surface with a layer ofthermoplastic adhesive. The discs or spots are punched from strips ofthe sheet material and, by the operation of the cutting punch, aresecured immediately to the cushion discs of the crown closures by thesimultaneous application of heat and pressure. After being initially putin. place by the punch, the liners are usually firmly Abonded to thecushions by a further application .of heat and pressure. The skeletonstrip from which the spots are cut, of course, consists of a composite,laminated sheet, including a c;ubstantial amount of thermoplasticadhesive. This skeleton-strip is either waste material or can bere-claimed onlyby separating the adhesive from the main body, atconsiderable expense.

In accordance with the present invention, un

coated spotting material, having no adhesive layer associated therewith,is secured` to the cushion discs of the crown closures. Thisisaccomplished by first applying to the cushion discs a layer ofthermoplastic adhesive, so that, as the hesive has been deposited andspread accurately on the cushion, or the layer of adhesive may bepermitted to cool and harden between the'time of its application to theVcushion and the deposit of the spot thereon. In other words, thecushions may first be provided with layers of thermoplastic adhesive andthen be stored until such time as it may be desired to complete theirfabrication. In such a case it is simply necessary) to preheat theclosures and the 'adhesive inthe spotting machine, in order to renderthe adhesive layer tacky so as to receive the desired spot material. 0nthe other handit a continuous operation `is "desired, the spot materialmay be applied substantially'immediately after the spreading of theadhesive on the cushion.

The adhesivewhich is 'preferably used with the method of the presentinvention is a thermoplastic composition of resins, waxes and/or gums,heated sufficiently to have the necessaryl v iluidity, withouttheaddition of solvents, -although in some cases, a thermoplasticadhesive in a solvent solution may be employed. The adhesive should havea melting point of around 128 uncoated sputan are punched from thestripand deposited onthe cushion layers, they adhere immediately to thethermoplastic adhesive pie` -viously positioned thereon and renderedtacky by the application of heat.` `'I'he spots so positioned .on thecushions are preferably subjected to further heat and pressure to firmlysecure them in position.

,The invention also includes novel means and methods of applying a layerof thermoplastic ad..V

hesive centrally over a predetermined portion of the surface of thecushion, in concentric relation to the edges thereof. To this end,anovelv form of spreading punch or/press is preferably employed. l v

The step of applying the spot to the layer of thermoplastic adhesive onthe face of the cushion V' may follow immediately after the layer ofadto 130 F. It must set rapidlyafter application to the cushion of thecrownv closure to produce a non-tacky film at room temperatures.

If the spots are subsequently applied, considery ably after theapplication of the adhesive layer,

the'adhesive must be of such composition that, when its surface isheated, it will become suinciently tacky to hold the metal or paperspots di rectly in the center of the cushion so that no off-centers areproduced when the crowns are moved along thel rack or guide rails of thema chine prior to entering the final pressure applying mechanism.

Asmstated above, it is preferred to usefan adhesive having no -solventassociated therewith,

but satisfactory'results have been accomplished by using the sameadhesive now conventionally employed with coated spotting material, suchas nitro-cellulose-resin thermoplastic cement which is usually `appliedin solution to one side of aluminum foil and'dried in an oven to expelthe solvents. If such an adhesive is used, the coated crown closure mustbesubjected to a. heat treatment after the spreading "operation has beencompleted and before the spots are applied, in

order to drive off the solvent.

Preferably, however, an adhesive containing no solvents and nonitro-cellulose is employed.

In addition to synthetic resins, the adhesive preferably contain-s a waxor other non-tacky substance in order to give a dry" or non-tackyemployed.

As the crowns enter the spotting machine, they reel to the adhesive whenset at room tempera@ tures, but without interfering with the adhesiveproperties. Such waxes as ceresin wax, or the @u Pont product Opal Waxmay be employed, or ethyl cellulose, benzyl cellulose or the like.,Such-resins as Rezyl and Arachlor may be mixed in substantially equalquantities to form the major portion of the adhesive. The two resins aremelted together to a liquid of fairly thin viscosity whichsolidiiies oncooling to a sticky gummy masshaving thermoplasticFproperties, and maybe remelted without sacriiice of its adhesive or thermoplasticproperties. A suitable formula is given by way oi example, as follows:

' Grams #is Rezyi resin (American Cyanamid Co.) l #4465- .;lrachlorresin (Swann Chemical Co.) lo

Ceresin wax At room temperatures this adhesive has a dry, waxy feel, butwhen subjected to heat and pressure, as in bonding aluminum foil orlaminated paper spots to cork cushions in a spotting machine, it hasremarkable adhesive properties and aords an excellent lbonding medium.

In the accompanying drawing, the method of the present invention isdiagrammatically illustrated and a diagrammatic apparatus lay-out isshown, but it must be understood that the invention is not'limited tothe specific details oi" construction shown, nor to the particularsequence of method steps.

Iny the drawing: Figure l is a diagrammatic vertical sectional view ofan apparatus for performing the method.

Figure 'I is a vertical sectional view of a pre' ferred form of adhesivespreader.

Crown closures comprising metal shells I0 and cushion liners I I. may befed from a storage re'- ceptacle and mechanical hopper down a chute to afeed dial, not shown. A suitable rack conveyor moves the crowns along aplatform I2, by astep by step movement, from right to left as viewed inFigure 1. The mechanism for moving the crowns in this manner is notshown in detail, since it forms no part of the invention claimed in thepresent application. A conveying mechanism such as is shown in thepatent to 1Johnson 1,852,578, vgranted April 5, 1932, may be pass undera preheater I3 and the temperature of the cork cushions is raised toprevent freezing of the thermoplastic adhesive when deposited thereon.'I'he heating means associated with the preheater I3 preferably is a gasburner.

Afterleaving the. preheater,'the crowns are conveyed to a positionbeneath the adhesive applying mechanism I4, which may be heated by a gasjet I5.- Next, the crowns come to rest under the adhesive spreader 'I 6,Vwhich may be heated by another gas burner I1. The spots are punchedagences from a strip by a punch b and simultaneously deposited upon thelayer of adhesive previously spread upon the cushion liners by thespreader lo. Next, the crowns with the spots slightly secured therein,preferably pass beneath a gas heated post heater le?. Finally, theheated crowns are received in thepressure dial 26;, where they aresubjected to sumcient pressure to iii-nary bond the spots to the cushionliners.

The means .for depositing the yadhesive certtrally of the cushion linersmay be substantially the same as the adhesive applying device shown inthe patent to McManus l.,efii,5l5, issuedl February d, 1923. Such amechanism may comprise a tube 3G adjustably mounted in a vertically reciprocablefarm di carried by the mechanism which operates the punchlil.v The upper end of the tube is open and is positioned directlybeneath the outlet 32 of an adhesive receptacle 33 which is heated by agas burner 3Q or the like. The receptacle 33 is provided with a valvecoutrolled outlet so that the drop by drop ow of adhesive from thereceptacle to the tube may be accurately controlled to correspond to thedeposit of adhesive in the crowns.

The lower end of the tube 3o carries a relatively movable needle valve35 which controls the deposit of adhesive in 'the caps. By adjust ingthe position of the tube gli, the length of the stroke or" the valvestem 35 may be varied,v there-1 by varying the amount of adhesiveapplied to each closure. As stated above, the details of I constructionof a suitable adhesive applicator are disclosed in the patent to McManus1,444,515.

The spreader I6 also is carried'by the arm 3l which reciprocatesvertically with the spotting material punch it. The spreader is mountedat the lower end of a Vertical post or plunger 36 having a bracket 3lsecured thereon. The post extends upwardly through a bushing 3B securedin a boss 39 integral with the arm. 3l whereby sliding movement betweenthe post and arm is permitted. A compression spring 40, disposed betweenthe boss 39 and the bracket 3,1, urges the plunger downwardly. Pins di,associated with the arm 3l, are disposed in downwardly opening channels42, on the undersurface of the bracket 3?, so that, on upward movementof the arm 3l, the bracket 31 and the post 36 are raised to lift thespreader it out of the crown closure.

As shown in Figure 7, the spreader is provided with a peripheralshoulder 45 adapted to engage the skirt of the crown shell for centeringpurposes'. Below the shoulder the end face of the spreader I6 isprovided with a concavity, formed by'a downwardly projecting, annularange 46, extending beyond the spreading surface 6l of the tool. The ange46 acts as an abutment vwall to limit the lateral spreading movement ofthe adhesive, under the iniiuence of pressure applied thereto by thesurface 4l. The edge of the ange 16 is relatively sharp and embedsitself into the cushion liner, forming therewith a tight Preferably, thediameter of thecoating so ap-G plied is les's than the diameter ofthespot to be positioned thereon, as hereafter explained.

The punch .I8 serves .to out out circular discs ofuncoated spottingmateriahsuch as aluminum aeeaeea foil orvvarnished paper, from anelongated stripv posits them on the adhesive layerl, spread on the linerby the spreader I6 yfrom the drop of adhesive SIIv deposited by :thedropper Il.' A

punch similar to that shown in the aforesaid Johnson patent may beemployed. The crowns with the spot liners positioned thereon are`carried beneath the heater I9. and then into the pressure "dial 2li.The latterv comprises ka rotary table 60 and a plurality of verticallydisposed pressure plungers 6I urged downwardly by compression springs 62and lifted by cam rollers 63 riding on a circular. cam track 64. yTheplungers 6I subject the assemblies to pressure during a single rotationof the table 6I), for a suilicient length of time to rmly bond the spotto the cushion liners.

Referring to Figures 2 to `6 inclusive, the previously assembled shellII) and cushion II is shown in `Figure '2, in condition ready ltoreceive a small body of adhesive from the adhesive applicator I4.` Asshown in Figure 3, the closure has received the body adhesive 50, and inFigure 4., the same' has been spread outfinto a circular layer 5Iv bythe spreader I6. Figure 5 shows the spotl 52 after it has beenpositioned in place by `the cutting punch I8. It should be noted thatthe margin 53 'of the spot 52 projects outwardly a slight `distancebeyond the corresponding concentric margin of the adhesive layer 50. InFig-v case it is only necessary to reheat the adhesive layers in orderto receive the liners.

It must be understood that the invention is not limited to the detailsof construction of the apparatus shown in the accompanying drawing anddescribed above; nor to the particular method steps described, butcovers 'all modiiications com- .ingwithin the scope 'of the appendedclaims and their equivalents. Wev claim:

l. The method of securing spot liners to-the cushions' o! crownclosures, which comprises heating the crown shells vand the cushionstherein, positioning a small body of hot, tacky, ther4 moplasticadhesive substantially centrally of the V cushion. subjecting the smallbody 4of adhesive so positioned to pressure between the cushion and asubstantially plane spreading surface disposed in .parallel relationthereto, thereby causing the adhesive to tiow laterally between thecushion and said surface and to spread laterally on the' surface of thecushion, and positively conlining by obstruction the extent of lateralflow,

thereby providing a coating of thermoplastic adhesive of deiinite sizeandeposition on the -faceot the cushion, depositing a spot linerconcentrically onsaid layer of adhesive and subjecting the assembly toheat and pressure to secure the spot liner tdthe cushion Awhen-theadhesive cools'.

2. The method of `securing spot liners to the cushions of crownclosures, whichcomprises de-` positing a body of hot, thermoplasticadhesive` on the face of the cushion, subjecting the small body ofadhesive so deposited to pressure between the face of the cushion and aplane spreading surface disposed in parallel relation to said face andmoved relatively toward the same, thereby causing vtheadhesive to flowlaterally and to spread over a portion of the face of thecushion,positively limiting by obstruction the extent'of lateral flowthereof,thereby providing a layer of adhesive having definitelypredetermined vmar-` gins, placing a spot liner upon said layer ofadhesive with its margins concentric to themargins of the layer, andsubjecting theassembly to heat and pressure to secure. the liner Ato thecushion when the adhesive cools. l

3. The method of securing spot liners `to the cushions of crownclosureswhich comprises depositing a body of hot, thermoplastic adhesiveon the face of the cushion, spreading the adl 4. 'I'he method ofsecuring spot liners to the I cushions of crown closures whichcomprisesde-` positing `a. body of hot, thermoplastic adhesive on theface of the cushionspreading the adhesive Alaterally over a portion ofsaid face by mechanical pressure applied thereto while simultaneouslypositively limiting by obstruction the extent of lateral flow, therebyproviding a layer of adhesive having definitely predetermined margins,

applying a.y spot liner to saidlayer of adhesive with its edgesconcentric to said margins, subjecting the crown closure, the layer ofadhesive and the spot liner to heat, and then pressing the liner uponthe layer of adhesive to bond the same to the cushion.

5. The method of securing spot liners to the cushions 'of crown closureswhich comprises preheating the crown shells and the cushions positioned'therein, `depositing a small body of h ot, thermoplastic adhesive on theexposed surface ofl the cushlonsubstantially at the center thereof,compressing the adhesive between the surface of the cushion and a membermovable toward the cushion and thereby spreading the adhesive radiallyfrom said center, positively restraining by obstruction the radialspread of the adhesivevalong a circular line concentric to and spacedinwardly from the circular margin of the cushion, positioning a circulardisc of spot lining material on said layer of adhesive with itsy marginconcentric to the layer and cushion, and

subjecting the assembly to pressure to adhesively vsmall body ofthermoplastic adhesives on said surface substantially at the centerthereof, disposing a circular barrier wall in engagement with thesurface of the cushion in concentric relation to the 'margin thereof,subjectingthe body" o!- thermoplastic adhesive to pressure between ionunder the influences of heat and pressure andfsubsequent cooling of theadhesive.

'1. In the manufacture of spot caps, the method of applying to thecushion in the ci'owi shell a 'layer of thermoplastic adhesive material,which comprises depositing a small body of thermoplasticadhesive on thecushion substantially at the center thereof, then positioning an annularwall against the surface of the cushion along a circular line spacedfrom and concentric with the margin thereof, applying mechanicalpressure to the previously deposited body of adhesive and therebycausing the same to iiow and spread radially outwardly from the centeragainst said wall, and limiting the outward spread of said adhesive bysaid wall, whereby the margins of the layer of adhesive aresubstantially concentric with the margins of the cushion.

8. An apparatus for securing spotliners to the cushions of crownclosures, comprising means for depositing small bodies of hot,thermoplastic adhesive substantially centrally of the surface of thecushions, means for compressing and spreading the bodies of adhesiveover the central portion of the cushions, said means comprising aplunger having a concave end face marginally dened by a circular edgeengageable with the cushions on'a circular linecon'centric to thecircular edge thereof to limit the outward spread of the adhesive underthe pressure of the plunger, means for depositing spots of sheetmaterial concentrically upon theadhesive layers, and means forsubjectingthe assemblies to heat and to pres- 'sure to adhesively unite the spotsrmly tothe cushions when the .adhesive cools.

9. An apparatus for coatinglthe. central portion of the exposed surfaceof a cushion disc in a crown closure with a layer of thermoplasticadhesive, comprising a die'adapted to spread over said surface apreviously deposited small body of tacky thermoplastic adhesive, saiddie being mounted for movement coaxially with respect to thel cushion,and means for moving Athe die toward the cushion, said die havingadownwardly projecting wall adapted to engage the surface of the cushionand to be embeddedltherein along a circular line concentric to themargin of the cushion, .said die having a spreading surface adapted tocompress the body of thermoplastic adhesive and to force the sameoutwardly against said downwardly projecting wall.

10. Apparatus. for coating the central portion of the exposed surface ofa cushion disc in a crown closure with a layer of adhesive, com- PriSingmeans for accurately positioning such a closure,v a plunger Ahaving animperforate end face mounted for movement 4toward the closure,

and means for moving the plunger towardjhe closure to engage the surfaceof the cushion in coaxialrelation, said plunger having a circularconcavity in its end face marginally dened by anedge projecting towardand engageable with the cushion along a circular line spaced inconcentric relation inwardly of the edge of the cushion, said edgeserving to limit thevoutvard spread of a small body of'adhesivepreviously applied centrally'to the exposed surface of the cushion andcompressed'upon the cushion L., pressure applied by said end face ofsaid plunger. ll. Apparatus for coating the central portion of the-exposed surface of a cushion disc in a crown closure with a layer ofthermoplastic adhesive, comprising means for positioning a small, hotbody of such adhesive substantially centrally of said surface, a plungermounted for movement toward the closure, means for moving the plunger toengage the surface of the cushion in coaxial relation, and means forheating the plunger, said plunger having an end `face bounded by a thinmarginal projection extending toward and engageable with the cushionalong a circular line spacedHin concentric relation inwardly of the edgeofy the cushion, said edge serving to limit the outward spread of saidbody'of adhesive when compressed upon the cushion by pressure appliedthereto by the end face of the plunger.,

12. An apparatus for applying center spot liners 'to crown closures,comprising means for conveying a line of closures step by step throughthe apparatus, means for heating the metal shells and the cushion linersas they enter the apparatus, means yfor depositing small bodies of hot,thermoplastic adhesive substantially centrally of the exposed surfacesof the cushion liners, means for spreading the bodies of therv moplasticadhesive over a centra] portion of the cushions and for positivelylimiting the extentv of such spreading, means for depositing center spotliners upon the adhesive in concentric re` lation thereto, and tothecushion liners, means' for heating the closures, the adhesive and thespot liners, and means for-subjecting lthe heated assemblies tosuflicientgpressure to firmly bond the spot liners to the cushionliners.

.13. Apparatus for securinga spot liner to a crown closure,vcomprisingmeans for depositing a body of heated thermoplastic adhesive ofpredetermined volume substantially centrally of the cushion liner intheclosure,. means for spreading the body of adhesive radially over acentral 44portion of predetermined diameter on said cushion and fordefinitely limiting the spreading of said adhesive to flow outwardlyuntil its margins 'i coincide with the margins of the spot liner.

FRANK J. G AV'IN.

SCOTI IRA WJLBUR. ROBERT HOLLAND.

